STUDIES OF PLANT LIFE. 
Why is it desirable to boil drinking water? 
Why are foods preserved by canning ? 
. Why is cold storage a means of food preservation ? 
. Explain the use of yeast in bread making. 
. Why must the bread mixture be set where it is 
warm, but not hot? 
. Name other uses of yeast. 
How is yeast prepared for use? Can yeast be 
made? Why? 
